Allow the use of different domains for the gitlab web interface and repository access

[Scharrels]

The self-hosted gitlab configuration asks for one url for both the web interface and repository access:

[gitrepo "myprecious"]
    type = gitlab
    token = YourSuperPrivateKey
    fqdn = gitlab.example.org

However, it is possible to host the gitlab web interface on a subpath of a domain: https://example.org/gitlab/

Similarly, it is possible to use an entirely different (sub)domain for the repository access: https://git.example.org/

I would suggest to support these possibilities in the git-repo configuration for self-hosted gitlab instances:

[gitrepo "myprecious"]
    type = gitlab
    token = YourSuperPrivateKey
    website = example.org/gitlab/
    repositories = gitlab.example.org

It might be nice to keep supporting fqdn as a shorthand, for backwards compatibility and for the common case, where website and repositories are hosted on the same domain, without subpaths.

[guyzmo]

Hosting gitlab as a path is discouraged and marked as experimental within gitlab documentation and setting up a rewrite rule towards a subdomain isn't really hard.

The main reason this hasn't been supported (yet) is because I prefer to focus on the general usecase (which is an instance hosted straight and single end point at the root path of a domain or subdomain).

All in all, I'm pretty sure it's possible to work that out (though that solution will have to also work with any other git service), but I won't make it a priority in my TODO list.